Update code review policies for sub-projects.

As agreed during the Stein PTG, this patch proposes an update to the
code review policies, aimed at minimizing the impact of code changes in
Neutron on the Stadium and other networking related projects.

Change-Id: I455a62daa9115962cd6347d1f3966dae533e4abb

doc/source/contributor/policies/code-reviews.rst

@@ -59,6 +59,27 @@ In addition to that, the following rules are to follow:
      that would help interested parties to identify their platform limitation
      in timely manner.
 
+* Special attention should also be paid to changes in Neutron that can impact
+  the Stadium and the wider family of networking-related projects
+  (referred to as sub-projects below). These changes include:
+
+  #. Renaming or removal of methods.
+  #. Addition or removal of positional arguments.
+  #. Renaming or removal of constants.
+
+  To mitigate the risk of impacting the sub-projects with these changes, the
+  following measures are suggested:
+
+  #. Use of the online tool `codesearch <http://codesearch.openstack.org>`_ to
+     ascertain how the proposed changes will affect the code of the
+     sub-projects.
+  #. Review the results of the non-voting check and 3rd party CI
+     jobs executed by the sub-projects against the proposed change, which are
+     returned by Zuul in the change's Gerrit page.
+
+  When impacts are identified as a result of the above steps, every effort must
+  be made to work with the affected sub-projects to resolve the issues.
+
 .. _spec-review-practices:
 
 Neutron Spec Review Practices